Currently, in evaluating communication systems, particularly wireless communication systems such as a Code Division Multiple Access (CDMA) system, it is necessary to simulate the noise that would be present if the system were loaded to various capacities. One manner to provide this simulation would be to put the desired number of subscriber units into the system. However, this would make the testing difficult to control and require a large area in which the subscriber units would be dispersed. The preferable way to accomplish this simulation, is to provide an OUNS device in the receiving stage of a transceiver.
A prior art method of accomplishing this is to inject noise from an OUNS device into the receiver prior to an Automatic Gain Control (AGC) stage. This prior art method measures the actual RF input level. The OUNS controller then uses this RF input level to determine the noise to be injected. To determine the RF input level, an additional receiver branch with AGC is used to provide feedback to the OUNS controller.
A problem with the current design is that the AGC devices are not accurate enough in the expected range of input RF input levels. In addition, it requires the addition of another receiver branch with AGC. This adds to the cost, complexity, and size of the receiver.